Activity-based probes methods

In principle, there are two methods for the AFM probing of amorphous layers, namely (i) an active probing, which probes the surface chemistry, and (ii) a passive probing, which probes the surface physics. The active AFM probing, which is essentially an extension of the AFM-based single molecule studies, relies on the measurement of LF by an AFM tip that is fimctionahsed with molecular recognition-active molecules (e.g., a potentially complementary DNA). 

Until recently, irreversible chemistries have not been applied to the systematic discovery of novel ligands. Instead, such methods have proven to be more useful for ligand-directed protein discovery, in which ligands specific to a certain protein or class of proteins are used to identify related proteins from a crude cell extract.14 511 Irreversible site-directed ligand discovery forms a continuum with affinity labeling and activity-based protein profiling, in which a reactive (often substrate-like) molecule binds covalently to a protein of interest.152 531 These techniques are typically used to probe enzyme mechanism or function or to identify a specific protein or class of proteins from a complicated mixture such as... 

The structure of this review is as follows in Section II, the activation and templating methods for preparing the porous carbons are briefly summarized. Section III surveys the structural characteristics of the porous carbons by using gas adsorption method. In Section IV, the molecular probe method and the image analysis method for quantitative characterization of the pore surface irregularity and the size distribution irregularity based upon the fractal theory are discussed in detail. Section V is devoted to... 

An additional difficulty in the determination of actual TOF values for zeolite catalysed reactions deals with the accessibility by reactant molecules to the narrow micropores in which most of the potential active sites are located. The didactic presentation in Khabtou et al.[37] of the characterization of the protonic sites of FAU zeolites by pyridine adsorption followed by IR spectroscopy shows that the concentration of protonic sites located in the hexagonal prisms (not accessible to organic molecules) and in the supercages (accessible) can be estimated by this method. Base probe molecules with different sizes can also be used for estimating the concentrations of protonic sites located within the different types of micropores, which are presented by many zeolites (e.g. large channels and side pockets of mordenite1381). The concentration of acid sites located on the external surface of the... 

No rigorous practical definition of acid strength exists outside of very dilute aqueous solutions where activity coefficients can be assumed to be unity. Each method of measuring the acid strength of surface sites is liable to give somewhat different answers, the results being qualitative at best. The dielectric constant of the medium, in which the acid or base probe is used influences the measured acid-base strength. 

Preparation of Probe. Probes for genomic Southern blots have been made by a variety of methods and must be of high specific activity. A simple method that yields a probe with a very high specific activity utilizes the polymerase chain reaction (PCR).16 An advantage of PCR over methods based on nick translation or primer extension is that only one strand of DNA is synthesized, so that reassociation of denatured single-strand probe in solution is minimized. 

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